Okay, the Lord says Mr. Misio ... I can add that additional protection through the so-called zeroing (so say old electricians) in the TNC lattice; TNS or TNC-S (here we can also connect the N conductor with the housing, the PE conductor should be connected) is now called quick disconnection. The point is that in the event of a voltage breakdown, a current will flow into the housing that will cause the circuit's protection to work. The maximum times in which a quick disconnection is to occur for our network (230 V between the phase conductor and the earth) is 0.4 sec. under environmental conditions of the first 1 and 0.2 sec. in environmental conditions 2.
These conditions depend on the ratio of the resistance of the human body to the earth. (in łazence it must be 0.2 sec).
For this to happen, it is necessary to check the fault loop impedance and check the protection characteristics at what time the trip will occur (at the current resulting from the fault loop impedance).
With the quick disconnect method, the housing of the device (e.g. washing machine) has a PEN conductor potential (so-called zero) for a given point in the network. You can check by putting an AC voltmeter between such a housing and, for example, a tap. Rather, the faucet has the potential of a zemi. it may be a few volts.
Due to grounding, the housing has ground potential, but the resistance of such grounding must be appropriate, it depends on the network layout. (E.g. in the TT system, the shutdown time should be no longer than 5 seconds) ".